function initFooter()
{
	var _main = document.getElementById('main');
	var _header = document.getElementById('header');
	var _footer = document.getElementById('footer');
	var _height = 0;
	var _hAuto = 0;

	function getHight(){
		if (window.innerHeight) _height = window.innerHeight;
		else _height = document.documentElement.clientHeight;
		return _height;
	}
	_main.style.height = getHight()-_header.offsetHeight -_footer.offsetHeight-100 +"px";

	function setHeight(){
		_main.style.height = "auto";
		_hAuto = _main.offsetHeight +_header.offsetHeight + _footer.offsetHeight;
		if (_hAuto < getHight()) _main.style.height = getHight()-_header.offsetHeight -_footer.offsetHeight-100 +"px";
	};
	setInterval(function(){
		setHeight();
	},1000)
}

if (window.addEventListener) window.addEventListener("load", initFooter, false);
else if (window.attachEvent) window.attachEvent("onload", initFooter);